Query for specific group membership, export to csv

I currently have a one liner that uses get-aduser to query for users that have not logged in and then I do some filtering. I have managed to get the memberof attribute to display correctly in a csv file. I would like to be able to sort on specific group membership. I orginally thought about splitting group membership into separate columns but I thought this might result in inconsistent results. How would I go about creating some custom columns in my csv file and doing boolean evaluation of specific group membership? If any more experienced powershell users have some better ideas than this, I would appreciate any help. I have about five groups that I want to be able to sort with.